Method of immediately writing or reading files on a disc-like recording medium having control information on defect management stored in a predefined location

ABSTRACT

A method of recording digital information signals on a removable rewritable disc like recording medium, the method including recording user data on a logical area of the disc and, prior to removal of the disc out of a recording/reproducing apparatus, finalizing the disc with a lead-in and lead-out area comprising predefined medium format data. A general purpose area within the logical area for other use than recording of user data, is being reserved. Such a use may be, for example, defect management. Further, the method involves interrupting recording a lead-in area or a lead-out area at predefined splice points whenever a request for user data is made.

This application is a continuation of U.S. application Ser. No.10/453,017, filed Jun. 3, 2003, now U.S. Pat. No. 6,724,701, which is acontinuation of U.S. application Ser. No. 09/873,565, filed Jun. 4,2001, now U.S. Pat. No. 6,594,209.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a method of recording digital informationsignals on a removable rewritable disc like recording medium, the methodcomprising submitting fixed sized packets of user information forrecording on the disc, the packets having a minimum packet size,allocating said packets to continuous sectors on the disc in a dataarea, said sectors having a minimum addressable sector size smaller thanthe minimum packet size, wherein said allocating comprises reallocatingdefect areas to a spare area on the disc, and recording said packets onthe disc along a spiral track.

The invention further relates to an apparatus for recording/reproducingdigital information signals on/from a removable rewritable disc likerecording medium, the apparatus comprising input means for receivingsignals representing fixed sized packets of user information forrecording on the disc, the packets having a minimum packet size,allocating means for allocating said packets to continuous sectors onthe disc in a data area, said sectors having a minimum addressablesector size smaller than the minimum packet size, defect managementmeans for reallocating defect areas to a spare area on the disc, andrecording means for recording the signals representing user data along aspiral track on the disc.

2. Description of the Related Art

The PC world needs a replacement for the floppy drive. A rewritablestorage medium of the disc-like optical type, such as the CD-RW, seemsto be a logical choice because the read function of the magnetic floppyis already replaced by the CD-ROM. All PC's today are equipped with aCD-ROM and applications and software are distributed on CD-ROM.Therefore, a recording medium like CD-RW or rewritable DVD, seems to bethe perfect media to fill in the needed write capability. MO andZIP/Jazz already tried to fill this gap, but they all miss compatibilitywith the installed base. That is exactly what CD-RW, for instance, candeliver with the installed base of over approximately 200 million CD-ROMdrives (MR1.0 compatible). RW media are cheap and the capacity issufficient for floppy use.

Furthermore, manufacturers of operating systems want to get rid oflegacy material like the floppy drive. For OEM companies, the idea isattractive, as they can replace the floppy drive, the CD-ROM and theDVD-ROM drive by a one spindle drive, like a Combi, and by a doublewriter in the future. It will also add a new feature to the drive otherthan the ever increasing speed.

There are products on the market (like DirectCD) which enable using aCD-RW like a floppy drive, but they don't behave the way one wouldexpect a CD floppy drive to behave. The access time is too low,formatting time is too long and, more important, the drive does not fitinto the strategy of current OS. The disc should be immediatelyavailable for dragging and dropping of files. A fast eject is required,deleting should be instant. Due to enable multiple drag and drop, adefect management is required. However, the defect management should bedone by the drive. This opens the way to use UDF 1.02 instead of UDF1.5,which will not be supported on the write side by Microsoft. Furtherbackground formatting must be done by the drive and not by theapplication or OS to minimize bus traffic, and interaction between thedrive and the OS. Finally, Read/Modify/Write for packets should be doneby the drive.

Such a method and apparatus is disclosed in European Patent ApplicationNo. EP 99203111.2, corresponding to U.S. Pat. Nos. 6,606,285 and6,760,288, and European Patent Application No. EP 00200290.5, bothincorporated by reference.

However, the method of defect management disclosed is limited toone-packet based replacements, the size of the replacement packets beingthe same as the size of the write-packet. For instance, in case ofCD-RW, both sizes are 64 kB or 32 sectors. Although this is sufficientto cover Disk-Over-Write (DOW) problems of RW media, it appears to beinefficient with respect to robustness for local physical defects, likefinger prints, scratches and media weak-spots. DOW tends to wear outsectors equally within one written packets. Thus, it makes a lot ofsense to replace the whole unity in one step, since the indication thata part (2 kB-sector) of the packet is wearing out can be interpreted asa wear-out warning for the whole packet. But due to the spiral-groovestructure of an optical record carrier, non-DOW defects, like the onesmentioned above, will typically appear on neighborhood tracks. Forexample, a scratch of 3.5 cm from inner to outer diameter across thedisk affects approximately 3.5 cm/1.5 μm=23300 tracks, in case of anCD-RW disk. This implies approximately 21000*64 kByte=1344 Mbyte. With a74 min CD-RW disc with 500 Mbyte user area and approximately 40 Mb sparearea, this is clearly not feasible.

SUMMARY OF THE INVENTION

In consequence, among other things, it is an object of the invention toobviate above-mentioned disadvantages. Accordingly, a method asdescribed in the opening paragraph, is characterized in that the methodfurther comprises the step of reallocating defect areas by a replacementarea in a spare area, the size of the replacement area beingsubstantially smaller than the minimum packet size. Correspondingly, anapparatus as described in the opening paragraph is characterized in thatthe defect management means are adapted to reallocate defect areas by areplacement area in the spare area, the size of the replacement areabeing substantially smaller than the minimum packet size.

Local physical defects, not effecting a whole packet, will then requireless spare area than if a whole packet would be replaced.

BRIEF DESCRIPTION OF THE DRAWINGS

These and further aspects and advantages of the invention will bediscussed in more detail hereinafter with reference to the disclosure ofpreferred embodiments, and in particular with reference to the appendedFigures, in which:

FIG. 1 shows a basic disc lay-out of a CD-ROM;

FIGS. 2A–2C show the lay-out of a Main Defect Table (MDT) according tothe invention;

FIG. 3 shows the Main Defect Table (MDT) packet organization accordingto the invention, showing repeated sectors;

FIG. 4 shows the Main Defect Table (MDT) packet organization accordingto the invention, showing the entries;

FIG. 5 shows the Main Defect Table (MDT) layout;

FIGS. 6A–6B show the composition of a Main Info Packet (MIP);

FIG. 7 shows the content of the Main Info Packet (MIP)/Second InfoPacket (SIP);

FIGS. 8A–8C show the changes with respect the Secondary Defect Table(SDT) and the Temporary Defect Table (TDT); and

FIGS. 9A–9B show important boot sectors on the disc and their remappedlocations in the spare area.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates, schematically, the basic format of a CD-ROM, asknown from the relevant standard, which is often denoted to as the‘Yellow book’, in analogy to the ‘Red book’ standard for the audio CD.Descriptions of the physical standard of the CD-ROM can be found in thepublic available documents ISO/IEC 10149, of the audio-CD in IEC 908.The physical standard for the recordable CD, denoted as the ‘Orangebook’, is disclosed in ISO/IEC 11172/1/2/3/. The standard for thelogical format of the CD-ROM is described in ISO-9660 (the High Sierrastandard) and for the recordable CD in ECMA 168/IS013940 (theFrankfurter proposal).

The data carrying area of the CD-ROM starts with a LEAD-IN area, a DATAAREA is available for user data and ends with a LEAD-OUT area.

The methods for Defect Management and Formatting are described in theaforementioned European Patent Application Nos. EP 99203111.2 and EP00200290.5, both incorporated by reference.

The defect sparing possibility of the method disclosed in theabove-mentioned applications, is limited to one packet-basedreplacements. In case of CD-RW, the packet size being 64 kB (32sectors), equal to the packet write block size. In case ofDisk-Over-Write (DOW) problems of RW media, this choice is sufficient.DOW tends to wear out packets equally within one written packet. Thus,it is practical to replace the whole unit in one step, since theindication that a part (for instance, a 2 kB sector) of the packet iswearing out, can be interpreted as a wear-out of the whole packet.

However, due to the spiral-groove structure of a CD, non-DOW defects,such as fingerprints, scratches and local media defects, will typicallyappear as short defects re-occurring on neighboring tracks. This meansthat within one spiral of a track, defects typically are located withinthe borders of one sector, locally preceded and followed by multiplesectors without defects. For example, for CD-RW with a 64 kB packetcomprises approximately 5 tracks at the inner circle and approximately 2tracks at the outer circle, typically only between 2 and 5 replacementsof 2 kB packets are needed for a packet affected by the defect. Thesurrounding data-sectors of the same packet need not to be replaced.

By choosing the size of a replacement area substantially lower than thepacket write size, more defect replacements can be handled. Forinstance, in case of CD-RW, a radial scratch of 3.5 cm from the inner tothe outer diameter across the disk, will claim approximately 40 Mb ofsparing area, in case of a 2 kB packet replacement. The amount ofcrossings of an 80 minute disc being: 3.5 cm/1.5 μm=23300 minusscratches in link blocks (−20%) plus scratches affecting 2 sectors onthe border (+10%)=21000. Thus requiring 21000 pointers, leading to aDefect Area size of 21000*2 kB=42 Mb. Available on a 74 min disc with auser area >500 Mb the amount of 48 Mb. In case of 64 kB replacements, ascratch of 1 mm will be sufficient to fully claim the same 40 MB sparingarea.

The choice for 2 kB sparing has the following consequences for drives.The defect table size needs to be relatively larger as each 2 kBreplacement space is a potential pointer in the table, when accountingfor the same amount of replacement area. As an extreme example, in thecase of DOW wear-out of a packet, the defect table will contain 32entry-positions instead of 1 kB in case of a 64 kB replacement system.

To solve this problem, the Main Defect Table (MDT) is allowed to growfrom 1 packet to 8 packets maximal. This is illustrated in FIGS. 2A–2C,showing, in FIG. 2A, the MDT layout with a fixed size according to themethod of defect management disclosed in the above-mentionedapplications. FIG. 2B and FIG. 2C show the MDT layout according to theinvention with a variable size, i.e., with a minimum size and a maximumsize, respectively. Next, consecutive MDT packets are added in theLead-In in a direction pointing to the inner diameter.

The disc starts with only one MDT packet (MDT1). Each packet isidentified with an order number (1 . . . 8) as will be shown withreference to FIG. 5

Further a Main Info Packet (MIP) replaces the Sentinel Packet (STL) asdisclosed in the above-mentioned applications, which will be explainedwith reference to FIGS. 6A–6B.

FIG. 3 shows the Main Defect Table (MDT) packet organization accordingto the invention, showing repeated sectors. Within each MDT packet, 4sectors are repeated 3 times in the depicted geographical order. Thishas the advantage of protecting against fingerprints. It is noted that arepeat factor of, for instance, 3 could also be chosen, being a matterof implementation.

All addressing is 2 kB based Logical Block Addressing (LBA). A completereplaced packet has 32 entries in the table. As an example, a packet maycontain 8*337=2696 pointers per packet, equivalent to a defect area of5.26 MB, handling a scratch of ½ cm.

FIG. 4 shows the Main Defect Table (MDT) packet organization accordingto the invention, showing the entries. The entries are ordered per 2 kBsector. Bit 4 and 5 indicate the status: replaced (‘00’) and marked(‘01’). These are ordered on ascending LBA and mixed in one block. Thisappears to be easier for the firmware. Other entries with value (‘10’)for bits 4 and 5, indicate available entries, which are ordered onreplacement LBA. Finally unavailable entries are marked with (‘11’).Preferably, drives should keep available replacements (‘10’) availableon sector base, which allows firmware to insert new defects easily.

FIG. 5 shows 5 the Main Defect Table (MDT) layout according to itscontent.

FIGS. 6A–6B show the composition of a Main Info Packet (MIP), replacingthe function of the Sentinel Packet (STL) of the method described in theabove-mentioned applications. As the Main Defect Table (MDT) cansignificantly grow into the Lead-In Areas, long detection times with aSentinel Packet (STL) may occur. The Main Info Packet (MIP) containsMain Defect Table (MDT) and Secondary Defect Table (SDT) packetpositions. The Main Info Packet (MIP) further contains version info. TheMain Info Packet (MIP) is repeated 32 times and is located on a fixedposition (last packet Lead-In Area) and cannot be moved or spared.

A duplicate is located as the Secondary Info Packet (SIP) on the outsideof the disc, see FIGS. 8A–8C. Write or read problems for MIP or SIPmeans end of write capability. Discs with problems in the housekeepingshould not be written on. However, the MIP and SIP are sparsely writtenas they only contain static information.

FIG. 7 shows the content of the Main Info Packet (MIP)/Second InfoPacket (SIP) per 2 kB sector.

Finally, FIGS. 8A–8C show the changes of the Secondary Defect Table(SDT) and Temporary Defect Table (TDT) as disclosed in theabove-mentioned applications. The status thereof being illustrated inFIG. 8A, while the new embodiments being illustrated in FIGS. 8B and 8C,with a minimum size and maximum size, respectively.

It is noted that the Sentinel Packet (STL) is replaced by a SecondaryInfo Packet (SIP), which has a fixed position, directly before the SUPpacket and cannot be moved or spared. The Secondary Defect Table (SDT)is still a copy of the Main Defect Table (MDT) but now SDT1 . . . SDT8is possible.

Growing into the replacements results in marking the replacements asunusable. An update counter is still used to detect a mismatch betweenMSD and SDT. The SDT is changed in the same way as the SDT.

Thus, a drive may replace complete 64 kB packets in case of DOW or incase of track problems during read and write and 2 kB replacements incase of scratches and fingerprints.

A further aspect of a medium formatted as disclosed above is thecross-platform disk compatibility with CD-ROM and DVD-ROM systems andlegacy CD-RW drives already in the market. Preferably, theread-capability of legacy systems should be maximal.

However, legacy read-capable systems might lack defect-remapping abilityor a PC-system might not have the suitable file-system to read back thedata as organized on disk. Therefore, to achieve read backcompatibility, a measure is proposed to make sure that a remapping-drivewill be installed on legacy PC-systems prior to reading the data contentof the disk, thereby avoiding data corruption due to incorrect physicaladdress of the data. Further a measure is proposed that suitable filessystems, if available, on the PC be used. And if no suitable file systemis available on the system, the user is guided, by a message, how toobtain and successfully install a suitable read-solution. Anothermeasure is proposed to ensure that the RW format will allow to makebootable disks which need to be readable on all CD-read capablePC-systems, and allow the current mechanism of CD-booting, such asspecified in the Bootable CD-ROM Format Specification, Version 1.0, Jan.25, 1995 from Phoenix Technologies and IBM, shortly referred to as“El-Torito”.

Legacy write capable systems might have an application package and filesystem, required to perform legacy drag and drop on CD-RW. However,these systems typically lack capability to apply defect remapping or toupdate data in the Lead-In or Lead-Out. Measures are proposed to preventthat legacy systems will write to this media-format, thus in this caselimit their capability to read-only solutions and thus avoidingincidental data corruption.

The method according to the invention, will be explained with referenceto FIGS. 9A–9B. The method makes active use of a number of key features,enables, by using defect management in combination with key sectors forISO 9660, data file systems and boot records. Some data-sectors play agating role for enabling booting and file system read and write. FIGS.9A–9B describe the case of CD-RW and UDF 1.02. However, otherembodiments may be obtained with other file systems, such as, forexample, FAT and other media, such as, for example, DVBD+RW and DVD-RW.

The key sectors are logical sector 17 for El-Toritoa booting, logicalsector 16 for IS09660 booting, logical sector 256 (ADVP), n or n−256(2nd ADVP) for UDF 1.02, with n being the last sector of the data zone.

The measure is to spare sector 16, 17, 256 and n (or n−256) by adedicated fill in of these sectors and write a replacement sector asfollows:

Sector number 16, being ISO structured, is used to upload a remap driveron the disk. This sector will be used by systems without a remapper. Thesparing location of sector number 16, also being ISO structured, is usedto store links to give a message or to a URL to download or install afile system. This replaced sector will be used by systems without UDF.

Sector number 17, being a boot sector, is used to store links to aboot-image, This sector is used by systems without a remapper. Thesparing location of sector number 17, is also a boot sector and containslinks to the same boot-image. This sector is used by systems with aremapper.

Sector number 256, n or (n−256) does not have any significant content.The sparing locations thereof however contain an UDF-ADVP and is beingused by systems with UDF.

FIG. 9A shows the location of the above-mentioned sectors on a discformatted according the format specified in the previous-mentionedapplications. FIG. 9B shows the remapping of these locations to sparearea according to an embodiment of the invention. Packet 1 is sparedfrom too many overwrites by file system used of other sectors. This isdone by replacing the complete packet as mentioned before. However, thesector retains boot and ISO 9660 capabilities. Sectors 256, n−256 and ncontains non UDF data, which prevents UDF to start and ISO 9660 to loadthe remapper driver. The General Purpose Area (GPA) contains theremapped sectors.

The effect of the above structure applied to CD-RW media, when insertedinto a drive with remapping capability or a legacy drive with remappingdevice-driver is (case 1):

a) enabling UDF reading when this file system is available on the PC;and

b) showing the content of the ISO structure when no UDF reader isinstalled on the system. In this case, the ISO-structure 2 can be usedto show a message to the end user (no UDF available, where/how to getone, eventually even a URL for downloading a suitable UDF reader-driverfrom the internet)

When the same disc is inserted into a drive without remappingcapability, for a system without remapping-driver, this will result in(case 2):

a) launching the remapper-driver on the disk, as a result of loading themedia by the PC-system via the ISO-link applied in ISO-structure-1(links into a remapper driver on disk, eventually accompanied by auser-message); and

b) after a boot, the PC will have full remapping capability, andresultantly from then act same as a solution according to “case 1”.

The effect during powering on of the PC-system is (case 3):

Due to the fact that original location and spared location are assuredto keep the same content (see definition above), independent of thepresence of a remapping capabilities of the PC-system (drive or driver),the PC-system will always obtain the correct boot-information (refEL-TORITO mechanism).

It is chosen to spare sector 17 at the formatting time of the media, inorder to prevent that the packet containing sector-17 can be worn out byDOW from other use prior to adding the boot-information. This way,sector 17 can be saved for later use, until the original sector-17 willbe filled in as boot sector. This way original location sector-17 cansafeguarded to allow legacy-system boot-compatibility

Obviously, after execution of the boot, the drive will return as “case1” or “case 2”.

Legacy drives/systems, although in some cases equipped with the suitableUDF file-system, should be prevented from writing to this medium (case4):

Legacy drives do not have all capabilities required to cope correctlywith the updating the defect-management-structures on the disk of thenew CD-RW format (no sparing capability+nor ability to update MDT in theLead-in).

As a result, it is wise to restricted these systems to read-only fromthis type of media (otherwise this could lead to incidental data-loss ordata-corruption). This can be achieved easily by making sure theread-remapper-driver (installed between drive and host) will not allowwrite commands to the drive. This way the drive will automatically belimited to read-only behavior.

Finally it is remarked that although the invention has been describedwith reference to preferred embodiments thereof, it is to be understoodthat these are not limitative examples. Thus, various modificationsthereof may become apparent to those skilled in the art, withoutdeparting from the scope of the invention, as defined by the claims. Forinstance a CD-RW may be replaced with a DVD-RW or the like. The methodmay be implemented in firmware in a drive or in an applicationcontrolling the drive.

The applicability of the same proposal to other file systems, forexample UDF 1.02 +CD-RW and UDF with DVD+RW is obvious.

The invention may be implemented by means of both hardware and software,and that several “means” may be represented by the same item ofhardware. Further, the invention lies in each and every novel feature orcombination of features. It is also remarked that the word “comprising”does not exclude the presence of other elements or steps than thoselisted in a claim. Any reference signs do not limit the scope of theclaims.

1. A method of providing control information on defect management on aremovable disc like recording medium, such as an optical disc, the disccomprising predefined locations for enabling disc booting and/or filesystem read/write, the method employing at least one of said locationsfor providing said control information.
 2. A method of providing controlinformation on defect management on a removable disc like recordingmedium, such as an optical disc, the disc comprising predefinedlocations for enabling disc booting and/or file system read/write, themethod employing at least one of said locations for providing saidcontrol information, wherein the recording medium is addressable bylogical sector numbering, the method employing logical sector numbered16 reserved by the ISSO 9660 system to provide said control information.3. The method as claimed in claim 2, wherein the method furthercomprises the steps of: recording pointer information in logical sectornumber 16; and recording, at the pointed location, a file systemcomprising said defect management.
 4. The method as claimed in claim 2,wherein said method further comprises the steps of: recording pointerinformation in logical sector number 16; and recording, at the pointedlocation, a message or a link to download a file system comprisingdefect management.
 5. The method as claimed in claim 2, wherein saidmethod further comprises the step of: Recording, in logical sectornumbered 17 reserved for disc booting, pointer information to aboot-image.
 6. The method as claimed in claim 2, wherein said methodfurther comprises the step of: Recording, in logical sectors numbered256, n or (n−256), n being the largest number of the user area, reservedfor UDF file system, non-UDF data.